Air conditioner having air expansion means



March 29, 1955 H. J. WOOD AIR CONDITIONER HAVING AIR EXPANSION MEANSFiled 001;. 20, 1952 IN V EN TOR.

United States Patent Oil 2,?04,925 AIR CONDITIONER HAVING AIR EXPANSIONMEANS Homer J; Wood, Sherman Oaks, Calif., assignor to The GarrettCorporation, Los Angeles, Calif., a corporation of CaliforniaApplication October 20, 1952, Serial No. 315,781

14 Claims. (Cl. 62--6) The present invention relates generally to an airconditioner, and is more particularly concerned with means for coolingair for enclosures.

It is an object of the herein described invention to provide an airconditioner which is especially suited for the cooling of enclosures,such as embodied in aircraft, which is susceptible of being incorporatedinto a compact self-contained unit suitable for mounting upon a truck ortrailer, by means of which it is readily mobile for movement from onelocation to another for connection through flexible duets with anaircraft enclosure during ground operations in hot or arid areas.

A further object is to provide novel means in an air conditioner forcontrolling the temperature and humidity of the conditioning airdelivered to the enclosure.

Another object is to provide a novel primary and secondary compressorarrangement in the coolant circuit of a heat exchanger, and novel meansfor controlling the pressure differential between the primary andsecondary compressors in such a way as to control and regulate thetemperature of conditioning air delivered to the enclosure with whichthe conditioner is connected. I

Still another object is'to provide in an air conditioner'novel de-icingmeans in the coolant circuit.

Briefly, the present invention comprises a portable or mobile airconditioner wherein the conditioning air is cooled and humidified in anevaporative heat exchanger having acoolant circuit arranged to takecoolant air from the conditioning air path through the heat exchanger,this coolant air being passed through power recovery means, such as anex'pansionturbine placed in the coolant flow path to the heat exchanger.A primary compressor is connected at the outlet of coolant flow from theheat exchanger, in series with a secondary compressor. The primarycompressor is dr1ven by the power recovery device, whereas the secondarycompressor is driven by an independent power source wh ch is alsoutilized to pump water or other evaporative medium to the heat exchangerand into the conditioning air' duct leading tothe enclosure, as well asdrive a fan for circulating air for the air conditioning through theheat exchanger.

A pro-swirl device is provided at the inlet of the secondary compressor,by means of which the flow may be varied in accordance with a controlcharacteristic, such as temperature variations in the enclosure, wherebyflow through the coolant circuit is controlled, and the concomitanttemperature of the conditioning air delivered to the enclosure.

A controlled bypass is also provided to conduct inlet conditioning airinto the expansion turbine, instead of partially cooled air, thusproviding a novel'arrangement for preventing de-icing on the exhaust ordischarge side of the expansion turbine.

Further objects of the invention will be brought out in the followingpart of the specification, wherein detailed description is for thepurpose of fully disclosing the invention without placing limitationsthereon.

Referring to the accompanying drawing, which is for illustrativepurposes only, the single figure schematically represents the componentparts and interconnections thereof in an air conditioner embodying thefeatures of the present invention; c

More specifically, theinvention' is shown as comprising an evaporativeheat exchanger in which a source of conditioning air is conductedinto'heat transfer relation with a suitable coolant. The heat exchangeris arranged with an inlet duct 11 for conditioning air, which may beselectively connected to take air directly from the surroundingatmosphere, or through a branch duct 12 recirculate air from anenclosure 13 with which the air conditioner is to be utilized.

The air supply may be regulated and controlled by means of conventionalmeans, in this case illustrated as a valve 14 which may be so adjustedthat the entire supply is made up of fresh air, or may be adjusted sothat the entire supply constitutes air which is recirculated from theenclosure 13. Moreover, if desired, the fresh air and recirculated airmay be proportioned.

The heat exchanger is provided with an outlet duct 15 for the enclosureconditioning air, and the inlet duct 12 and outlet duct 15 may beconnected by means of flexible duct connections with the enclosure which.is to be conditioned. .Movement of enclosure conditioning air throughthe heat exchanger is accomplished by means of a suitable fan 16 in theinlet duct 11, this fan being driven by suitable independent power means17, such asa reciprocating engine, which is connected with the fanthrough a suitable transmission 18.

The fan 16 raises the pressure of supplied air sufliciently to overcomesubsequent pressure losses due to the passage of the air through the airducts, heat exchanger, filters, etc. in the flow path of enclosureconditioning air. From the fan, the air passes into the heat exchanger10, where the required reduction in temperature and humidity takesplace, and then is discharged into the enclosure. From the enclosure itmay be recirculated or discharged directly to atmosphere.

The coolant medium, in this instance air, is supplied to an inlet duct19 from which it is conducted through a first pass 20, and thencethrough a second pass 21 to an outlet duct 22.

Normal supply of coolant air is 'bled'from the conditioning air passageof the heat exchanger from a point between the passes 20 and 21 througha bleed 15 energy which may be utilized for a useful purpose.

duct 23, so that the coolant air will have been partially cooled byhaving passed through the coolant pass 21.

The coolant air is conducted to a power recovery device 24 whichconsists of an air expansion turbine which acts to further cool thecoolant air and in so doing convert energy from the coolant intomechanical The discharge side of the power recovery device is connectedto the inlet duct 19.

Th outlet duct 22 is connected with the inlet of a primary compressor 25which is motivated by the power recovery device 24.

The coolant air discharge from the power recovery device 2 l, prior toIts entering the respective passes 20 and 21, is thoroughly saturatedwith water which is introduced through nozzles 26 and 27 by means ofwhich the water is sprayed into the heat exchanger tubes where itsevaporation results in further cooling. Water is supplied to the nozzles26 and 27 from'a suitable pump 28, which is also driven from thetransmission 18, this pump having its inlet connected with a suitablesource as represented by the tank 29. Excess water from the heatexchanger drains back into the tank 29 through drain lines 30.

In addition to the introduction of water into the coolant circuit, wateris also sprayed into the outlet duct 15 for enclosure conditioning airfrom a nozzle 31. The supply to the nozzle 31 is regulated by means of asuitable valve 32 under the control of a humidity sensing device 33located in the enclosure 13.

In order to obviate any tendency for ice to form in the inlet duct 19,means are provided for controlling the temperature of coolant air supplyto the power recovery device 24. For such purpose, a bypass 34 isconnected from the inlet duct 11 of the heat exchanger to the bleed duct23, thus enabling coolant air to be supplied directly to the powerrecovery device prior to its being partially cooled in the pass 21. Flowof air through the bypass 34 is controlled by a suitable valve 35 whichis motivated by an actuator 36 under the control of a thermostat 37positioned in the inlet duct 19. i

The present invention employs a unique arrangement Patented Mar. 29,1955 for controlling the flow of coolant through the cooling passages ofthe evaporative heat exchanger 10, and concomitant temperature ofconditioning air delivered to the enclosure. If a secondary compressor38 is now connected in series with the primary compressor 25, as shown,any change or variation of fiow through the secondary compressor willhave a regulating etfect upon the flow through the primary compressor.

Various means may be utilized to change the flow through the secondarycompressor. For example, the compressor speed may be varied orconventional throttle valves may be utilized. In the illustratedembodiment, the primary compressor 25 is shown as having its outletconnected to the inlet of the secondary compressor 38 through apre-swirl device 39 having a plurality of angularly adjustable vanes inthe path of flow of air entering the secondary compressor.

The angular position of these vanes varies the amount of swirl and has acontrolling effect on the flow through the secondary compressor. Thesuction created by the secondary compressor is thus varied, and byvarying the discharge pressure head existing at the outlet of theprimary compressor 25, the flow of coolant through the cooling passagesof the evaporative heat exchanger is effectively controlled. The use ofa preswirl device is advantageous in that it substantially reduces thepart-load power demand upon the power means 17, in contrast to theaction of simple throttling means such as, for example, a valve placedin the connection duct between the primary compressor 25 and thesecondary compressors 38.

The position of the vanes 40 is controlled by means of a suitable poweractuator 41 arranged to be adjusted to a desired vane setting means of amanually operable temperature selector 42, or automatic regulation maybe obtained by controlling the actuator 41 from a conventionaltemperature sensing device 43, as shown in dotted lines.

The components of the air conditioner, as described above, are of suchcharacter as to enable their being assembled into a compact unit whichmay be mounted on a truck or trailer to permit ease of portability andmovement to the aircraft where it is to be utilized for conditioningenclosures during ground operations.

Various modifications may suggest themselves to those skilled in the artWithout departing from the spirit of my invention, and, hence, I do notwish to be restricted to the specific form shown or uses mentioned,except to the extent indicated in the appended claims.

-I claim:

1. An air conditioner, comprising: a heat exchanger having aconditioning air passage selectively connectable on its inlet side withan enclosure and with atmosphere, and on its outlet side with saidenclosure, and having a coolant passage; means for moving air throughsaid conditioning air passage; an expansion turbine having an inletconnected to receive conditioning air from said air moving means, and anoutlet connected to discharge into said coolant passage; first andsecond compressors connected to successively receive coolant from saidcoolant passage, one of said compressors being driven by said turbine;independent power means for driving the other of said compressors andsaid air moving means; and means for regulating the air flow through thecompressor driven by said power means.

2. An air conditioner, comprising: an evaporative heat exchanger havinga conditioning air passage, the outlet of which is adapted forconnection with an enclosure, and a coolant passage: conduit means forconducting an evaporative medium to said coolant passage and to theoutlet of said air conditioning passage; an expansion turbine having aninlet connected to receive partially cooled conditioning air from saidheat exchanger and an outlet connected to discharge into said coolantpassage; a compressor connected to receive coolant from said coolantpassage, said compressor being driven by said turbine: a secondarycompressor driven by independent power means. connected to receive thedischarge from said first compressor; means for varying the flow throughsaid secondary compressor; a pump for said evaporative medium driven bysaid power means, said pump having its discharge connected to saidconduit means; and means for controlling the supply of evaporativemedium to said air conditioning passage outlet in response to humidityconditions in said enclosure.

3. An air conditioner, comprising: an evaporative heat exchanger havinga conditioning air passage, the outlet of which is adapted forconnection with an enclosure, and a coolant passage; conduit means forconducting an evaporative medium to said coolant passage and to theoutlet of said air conditioning passage; an expansion turbine having aninlet connected to receive conditioning air from said heat exchanger andan outlet connected to discharge into said coolant passage; a compressorconnected to receive coolant from said coolant passage, said compressorbeing driven by said turbine; a secondary compressor driven byindependent power means, connected to receive the discharge from saidfirst compressor; means for varying the flow through said secondarycompressor; and a pump for said evaporative medium driven by said powermeans, said pump having its discharge connected to said conduit means.

4. An air conditioner, comprising: an evaporative heat exchanger havinga conditioning air passage, the outlet of which is adapted forconnection with an enclosure, and a coolant passage; conduit means forconducting an evaporative medium to said coolant passage; an expansionturbine having an inlet connected to receive conditioning air from saidheat exchanger and an outlet connected to discharge into said coolantpassage; a compressor connected to receive coolant from said coolantpassage, said compressor being driven by said turbine; a secondarycompressor driven by independent power means, connected to receive thedischarge from said first compressor; means for varying the flow throughsaid secondary compressor; and a pump for said evaporative medium drivenby said power means, said pump having its discharge connected to saidconduit means.

5. An air conditioner, comprising: a heat exchanger having aconditioning air passage, the outlet of which is adapted for connectionwith an enclosure, and a coolant passage; an expansion turbine having aninlet connected to receive partially cooled conditioning air from saidheat exchanger and an outlet connected to discharge into said coolantpassage; a compressor connected to receive coolant from said coolantpassage, said compressor being driven by said turbine; a controlledsupply bypass connecting said expansion turbine inlet with theconditioning air inlet of said heat exchanger; a secondary compressordriven by independent power means connected to receive the dischargefrom said first compressors; and temperature control including means forvarying fiow through the secondary compressor.

6. An air conditioner, comprising: a heat exchanger having aconditioning air passage, the outlet of which is adapted for connectionwith an enclosure, and a coolant passage; an expansion turbine having aninlet connected to receive partially cooled conditioning air from saidheat exchanger and an outlet connected to discharge into said coolantpassage; a compressor connected to receive coolant from said coolantpassage, said compressor being driven by said turbine; means forvariably controlling flow of said coolant; a controlled supply bypassconnecting said expansion turbine inlet with the Conditioning air inletof said heat exchanger; and means controlling said bypass in accordancewith temperature conditions associated with the discharge from saidturbine.

7. An air conditioner, comprising: a heat exchanger having aconditioning air passage, the outlet of which is adapted for connectionwith an enclosure, and a coolant passage; an expansion turbine having aninlet connected to receive partially cooled conditioning air from saidheat exchanger and an outlet connected to discharge into said coolantpassage; a compressor connected to receive coolant from said coolantpassage, said compressor being driven by said turbine; means forvariably controlling the flow of said coolant; and a controlled supplybypass connecting said expansion turbine inlet with the conditioning airinlet of said heat exchanger.

8. An air conditioner, comprising: a heat exchanger for conductingconditioning air for an enclosure and a coolant into heat transferrelation; work extraction means driven by flow of coolant to said heatexchanger; a primary compressor driven by the work extraction meanspositioned in the flow of coolant from said heat exchanger; a secondarycompressor connected in series with said primary compressor; andangularly variable vanes associated with the inlet of said secondarycompressor for varying its flow characteristics.

9. An air conditioner, comprising: a heat exchanger for conductingconditioning air for an enclosure and a coolant into heat transferrelation; expansion cooling means driven by flow of coolant to said heatexchanger; means for compressing the coolant from the heat exchanger insuccessive stages; and means for variably throttling flow through acompressing stage subsequent to the first stage in accordance withtemperature variations from a predetermined norm.

10. An air conditioner, comprising: a heat exchanger for conductingconditioning air for an enclosure and a coolant into heat transferrelation; expansion cooling means driven by flow of coolant only to saidheat exchanger; means for compressing the coolant from the heatexchanger in successive stages; and means for variably throttling flowthrough a compressing stage subsequent to the first stage to vary thecooling efiect of said coolant in said heat exchanger.

11. An air conditioner, comprising: a heat exchanger for conductingconditioning air for an enclosure and coolant into heat transferrelation; work extraction means driven by flow of coolant to said heatexchanger; means for compressing the coolant from the heat exchanger insuccessive stages, said compressing means being motivated in part bysaid work extraction means; and means for controlling flow in a finalstage of said compressing means.

12. An air conditioner, comprising: a heat exchanger for conductingconditioning air for an enclosure and a coolant into heat transferrelation; work extraction means driven by flow of coolant to said heatexchanger; a primary compressor driven by the work extraction meanspositioned in the flow of coolant from said heat exchanger; anindependently driven secondary compressor in series with said primarycompressor; and means for varying flow through said secondary compressorin accordance with enclosure temperature variations.

13. An air conditioner, comprising: a heat exchanger for conductingconditioning air for an enclosure and a coolant into heat transferrelation; work extraction means driven by flow of coolant to said heatexchanger; a primary compressor driven by the work extraction meanspositioned in the flow of coolant from said heat exchanger; a variableflow secondary compressor connected in series with said primarycompressor; and means for adjusting the secondary compressor flow inaccordance with different temperatures.

14. An air conditioner, comprising: a heat exchanger for conductingconditioning air for an enclosure and a coolant into heat transferrelation; work extraction means driven by flow of coolant to said heatexchanger; a primary compressor driven by the work extraction meanspositioned in the flow of coolant from said heat exchanger; and avariable flow secondary compressor connected in series with said primarycompressor.

References Cited in the file of this patent UNITED STATES PATENTS2,453,923 Mayo Nov. 16, 1948 2,485,590 Green Oct. 25, 1949 2,503,250Eckert Apr. 11, 1950

